<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        
        div{
            width: 200px;
            height: 100px;
            background-color: red;
           /* float: left; */
           /* border: 1px solid red; */
           /* position: absolute; */
           /* overflow: hidden; */
           /* display: inline-block; */
           /* padding-top:100px;(改高度) */
        }
       
         p{
            background-color: blue;
            width: 50px;
            height: 50px;
            margin-top: 50px; 
            /* float: left; */
            /* position: absolute; */
            /* display: inline-block; */
       
        }
    </style>
</head>
<body>
    <div>
        <p></p>
    </div>
</body>
</html>